Memory T cells show the highest sensitivity to hIL4I1 activity. Positively purified CD4⁺, CD8⁺, memory CD45RO⁺, and naive CD45RA⁺ T lymphocytes were incubated for 3 hours with mock beads (▴) or hIL4I1 beads (■) through a 0.4-μm transwell and proliferation was measured by ³H-thymidine incorporation. Results are expressed as the average cpm of quadruplicates ± SD. A representative experiment (of 4) is shown. *P < .05.